This invention concerns modular plastic conveyor belts and the integrally molded modules which are assembled together, usually by connecting rods or pins, to form such modular belts. Specifically the invention is concerned with such a modular belt. that travels around curves (known as a radius belt) and is well adapted for use on spiral (helical) conveyor belt systems.
Conveyor belts of the general type addressed by this invention are shown in U.S. Pat. Nos. 4,901,844, 5,181,601, 5,310,045 and 6,484,379. Modular belt design, for relatively tight turns in radius belts, focuses on tight nesting together at the belt's inner edge, tight turn ratio, adequate beam strength to support items carried on the belt, adequate tension strength in the belt (both in turning and straight travel), air flow through the belt, and minimizing belt chatter at the inner edge on a spiral, edge-driven belt. Previous belts have not exhibited the efficient design of the present invention, particularly for spiral system application.
The following patents have some relevance to the subject matter of the present invention: U.S. Pat. Nos. 4,276,980, 4993,544, 5,217,110, 5,346,059, 5,645,160, 5,906,270, 5,921,379 and 6,216,854.